its long form of SQL case statement...just for an example ( short)

SELECT Employee_Name, CASE Location
WHEN 'nepal ' THEN Bonus * 2
WHEN 'everest' THEN Bonus *, 5
ELSE Bonus
END
"New Bonus"

Syntax for STUFF function in an SQL server

STUFF (String1, Position, Length, String2)
String1 - String to be overwritten
Position - Starting location for overwriting
Length - Length of substitute string
String2- String to overwrite.

pull your data in following syntax ( ur data is too long ) n try to solve this in following syntax

UPDATE STATISTICS table_or_indexed_view_name
[
{
{ index_or_statistics__name }
| ( { index_or_statistics_name } [ ,...n ] )
}
]
[ WITH
[
FULLSCAN
| SAMPLE number { PERCENT | ROWS }
| RESAMPLE
[ ON PARTITIONS ( { | } [, …n] ) ]
| [ ,...n ]
]
[ [ , ] [ ALL | COLUMNS | INDEX ]
[ [ , ] NORECOMPUTE ]
[ [ , ] INCREMENTAL = { ON | OFF } ]
] ;

similar weather example to your question is given below try to solve this way

#include
#include
EXEC SQL BEGIN DECLARE SECTION;

long station_id;
long mon;
float temp;
float rain;
char city_name[21];
long SQLCODE;
EXEC SQL END DECLARE SECTION;
main()
{
/* the CONNECT statement, if needed, goes here */
strcpy(city_name,"Denver");
EXEC SQL SELECT ID INTO :station_id
FROM STATION
WHERE CITY = :city_name;
if (SQLCODE == 100)
{
printf("There is no station for city %s\n",city_name);
exit(0);
}
printf("For the city %s, Station ID is %ld\n",city_name,station_id);
printf("And here is the weather data:\n");
EXEC SQL DECLARE XYZ CURSOR FOR
SELECT MONTH, TEMP_F, RAIN_I
FROM STATS
WHERE ID = :station_id
ORDER BY MONTH;
EXEC SQL OPEN XYZ;
while (SQLCODE != 100) {
EXEC SQL FETCH XYZ INTO :mon, :temp, :rain;
if (SQLCODE == 100)
printf("end of list\n");
else
printf("month = %ld, temperature = %f, rainfall = %f\n",mon,temp,rain);
}
EXEC SQL CLOSE XYZ;
exit(0);